Depends on your definition of big. LOL Of course the odds are against you to win the grand prize, but at least you've won something!
Probably my biggest win was from MyBargainBuddy. One month (think it was May), I won the monthly drawing for a sapphire/diamond bracelet. Also earlier this year (April), I won 2 tickets to Champions on Ice through a local TV station. That wound up being a bust though as we showed up with tickets in hand on that day and it had been cancelled.